Power walking is an unparalleled aerobic conditioning activity. Its calorie burn and weight-loss potential are similar to those of a running program, yet it's much easier on the body because there's about half the impact and wear and tear on your joints.

When you power walk, you generally move along at a fast pace of 4.4 to 6.0 miles an hour, covering one mile in 10 to 13.6 minutes. Some scientists speculate that you burn one and a half to two times as many calories power walking as regular-paced walking because you cover a greater distance in the same amount of time. Power walking also tones your muscles -- buttocks, thighs, hips, shoulders, upper back and abs -- for a sleeker body shape.

You probably will see a marked increase in tone and a decrease in body fat within six to eight weeks of adding one to three power walks a week into your overall walking and workout program. Each power walk should last from 20 to 60 minutes, including your slower-paced warm-up and cool-down. Serious walkers and anyone on a real weight-loss kick may want to do four to five power walks weekly.

Form is the key to getting the most from power walking. Review the following head-to-toe checklist before you walk and every 10 minutes or so while you walk. Besides making you look like a pro, good technique will help you move along faster with less effort and minimize your risk of injury:

• Head: Keep your head up and centered between your shoulders. Keep your chin up, and focus your eyes straight ahead. Your head and neck should "float" above your shoulders in a relaxed, easy manner.
• Shoulders: Keep them back and down. Don't allow them to round forward or creep up toward your ears.
• Chest: Your chest should be naturally lifted, as if a string were attached to the center, gently pulling it upward.
• Arms: Your arms should be bent at slightly less than 90 degrees. Swing them back and forth -- not side to side -- like pendulums, and keep them close to your body. At the top of the arm swing, your elbow will be level with your breastbone; at the bottom of the arm swing, your hand will brush your hip. Swing your arms briskly and definitely. Remember: In power walking, your feet follow your arms. In other words, you use your arms to propel your body forward.
• Hands: Keep them loosely cupped. Pretend you're holding a butterfly that you don't want to let escape but you don't want to crush either.
• Abdominals: Lean forward slightly so that you feel as if you are "tumbling forward in control" as you walk. Pull your belly button gently in toward your spine to help protect your lower back.
• Hips: Because your stride is quick and linear, move your hips in a sort of exaggerated wiggle. Use your hips to propel you forward so that you walk at a fast rate.